1. Field of the Invention
The present invention relates to a low construction of power supply; more particularly, to a TFT display with low loss construction of power supply to be used in monitoring in a power saving mode of the system.
2. Description of Related Art
Accompanying the flourishing of the industry, monitors have been transformed from the traditional CRT to the contemporary LCD. As shown in FIG. 1, an LCD 10 uses cold cathode rays 20 to radiate light, however, a supply voltage as high as 1200 volts DC has to be provided by a power supply device 110. One inverter 19 is thus required to transform the direct low-voltage (such as 24 volts) to high-voltage wherein the low voltage of 24 volts is provided by a transformer rectifier circuit 12. The transformer rectifier circuit 12 receives AC voltage inputted by an external device and is then processed by a rectifier filter circuit 11. After the AC voltage is transferred to the transformer rectifier circuit 12 and then processed by a feedback controller 13, the AC voltage is transformed to DC voltage and transferred to a frequency modulator 19 to provide the cold cathode rays voltages for processing displaying functions.
When the LCD 10 is not in use, whether it is turned off manually or shifted into a stand-by mode by the computer mainframe, both statuses are called a power-saving mode. As shown in FIG. 1, with the structure of the prior LCD 10 and its power supply 101, when LCD 10 is in the power-saving mode, a voltage of 5 volts needed by the microprocessor 18 is still required to be transferred from the 24 volts transformer rectifier circuit 12 to a 5 volts rectifier filter circuit 14. When transformer rectifier circuit 14 receives the 24 volts voltage from a transformer rectifier circuit 12, the voltage will be transformed into 5 volts and then outputted to a microprocessor 18. Moreover, due to the 5 volts voltage being unstable when first outputted, the feedback controller 15 is used to gradually modulate the voltage to a stable state. Therefore, although the prior art is in power-saving mode, it still requires the 24 volts transformer rectifier circuit 12 to provide the 5 volts voltage, meaning the 24 volts transformer rectifier circuit 12 still has to continue to function. Thus, although the inverter 19 is power-off when the prior LCD 10 is in its power-saving mode, there will still be some leaking current and the occurrence of power consumption due to the necessity of the continuing work of the transformer rectifier circuit 12. Power consumption not only causes higher expense for the user, but also produces unnecessary waste of resources that results in problems during use.